Attach nodes not showing?

[Rutabaga22]

When I merge a launch vehicle into my satellite the attach nodes of the subassembly don't show.

[Geonovast]

Only the node(s) on the root part of the subassembly will show, by design.  If you need to attach the subassembly with a different part, you can use the re-root tool on it, and then attach it how you want.

[jimmymcgoochie]

Either re-root the subassembly so the part you're going to attach it by is the root part, or use the move tool to take each part off the subassembly and stack it back up on top of the main vessel (a tedious and potentially craft-breaking process, not one I recommend unless there's no other option).